South Wales Police has become the third Welsh police force to introduce Tasar stun guns.

The force, the largest in Wales, is to issue the 50,000-volt guns to officers who are already trained in firearms.

Tasers temporarily disable a suspect with an electric shock delivered by two barbed darts trailing wires.

North Wales Police was the first Welsh force to use them, before Gwent Police adopted them in August. The Dyfed-Powys force is training officers to use them.

The darts fired by a Taser gun trail a wire up to 21ft long down which a 50,000-volt electric current is delivered for five seconds. The electrical current can penetrate clothing up to two inches thick

Amnesty International claims the guns have been linked to more than 70 deaths in America and Canada.

But many senior police officers see the weapons an effective alternative to lethal force for armed officers dealing with a potentially violent suspect.

Three of Wales' four force now use Taser stun guns

North Wales Police was one of the first UK forces to use the weapons on the streets when a man in Rhyl was fired at three times in August 2003.

The man was examined later by a police surgeon for minor injuries but was found to be otherwise fit and well.

South Wales Police has almost 3,500 officers but said only those trained in using firearms would be allowed to handle Taser stun guns.

'Baton gun'

A statement said: "The majority of forces in the UK have or are now in the process of deploying them as a less than lethal option where the authorisation of firearms has been granted."

The force's operations manager, Chief Superintendent Graham Davies, said the stun guns would be "deployed alongside conventional firearms and the baton gun and should not be seen as a replacement for such weapons".

He said: "Taser will provide another less-than-lethal option which will assist in the firearms officer's assessment and safe resolution of serious incidents without recourse to more lethal force."